Analysis of flapping flight of butterfly based on experiments and numerical simulations

The flapping flight of butterfly is an example of Mobiligence in which the environment is the generated flowfield. Actually, it essentially has the same structure with other Mobiligence subjects, e.g., to emerge the flapping flight from the interaction of the nervous system, body, and environment. This research analyzes the mechanism to emerge the flapping flight of butterfly from this viewpoint. Concretely, this study investigates the following two issues by the biological analysis through experimental observations of living butterflies and by the systems engineering or synthetic approach. An experimental system with a low-speed wind tunnel is constructed to measure the motion and aerodynamic forces of actual butterflies quantitatively. A 3D mathematical model is constructed to analyze the stability of actual free-flying butterflies and so on. Its validity and accuracy are examined by comparing with the obtained experimental data. Moreover, a periodic flapping flight is realized by using the obtained model. It clarify that the flowfield with vortex street induced by flapping effects on the stability of flapping flight. In addition, wing torsion caused by structural flexibility is also introduced to the model and its effect on the flapping-of-wings flight is examined.